What is overlock?
An overlock — or serge — is a stitch that joins two pieces and wraps the raw edge in looped thread in a single pass, trimming as it goes. It stretches with the fabric, so it is the standard seam for knits: the shoulders, sides and sleeves of every tee and hoodie.
Why it matters
Seam quality is construction quality. A 4-thread overlock with the right stitch density holds through years of wear; a loose 3-thread one on a heavy fleece fails at the armhole.
On our floor
4-thread overlock at 10–12 stitches per inch on main seams; specified in every tech pack we produce.
Common questions
- Overlock or flatlock?
- Overlock inside a seam for strength; flatlock where the seam lies against skin, as in activewear.
- What is a 4-thread overlock?
- An overlock with two needles and two loopers — stronger than 3-thread, standard for garments.
- Can overlock seams be topstitched?
- Yes — a coverstitch over the hem and cuff is standard on hoodies.
- How do I check seam quality on a sample?
- Stretch the seam: threads should hold without popping. Look for even stitch density and no missed loops.
Related terms
flatlock
A flatlock seam joins two pieces edge to edge with a flat, ladder-like stitch so there is no ridge on the inside. It is used where the seam…
bar tack
A bar tack is a short, dense block of zigzag stitching — about a centimetre — sewn over a point that takes strain: the corners of a…
coverstitch
A coverstitch is the pair of parallel stitch lines you see on the outside of a t-shirt hem, cuff or neckband, with a looped thread covering…
cut and sew
Cut and sew means the garment is made from fabric — cut to a pattern and sewn — rather than bought as a finished blank and decorated. It is…
Where this applies
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